Pool-cleaning robot and method for detecting halting of such a robot

ABSTRACT

The invention relates to a pool-cleaning robot comprising a transport system that comprises at least one idle transport wheel train, a detritus suction system, and a system for detecting halting of said cleaning robot, the detection system comprising at least one transceiver of a light ray along an emission axis and at least one target that is secured to the transport wheel train, is aligned with said emission axis, and is suitable for reflecting said light ray so as to detect rotation of said transport wheel train.

TECHNICAL FIELD

The present invention concerns the field of robotic pool cleaning. Theinvention, more specifically, attempts to reduce the pool-cleaning time.

Reminder: a pool has a bottom that is usually horizontal and sides thatare usually vertical. During use of a pool, detritus (leaves, grass,soil, etc.) is deposited on the bottom of the pool, which makes it lookbad. A cleaning robot allows detritus to be removed by moving around theentire bottom surface of the pool. From the prior art we know of anautonomous pool robot that can change its direction of movement in orderto clean the entire bottom surface of the pool. Such a pool robotcomprises a management module that allows transport commands to betransmitted successively. For example, the management module orders therobot to move three times from the back to the front for a duration of30 seconds during a first movement phase, and then to turn right duringa second movement phase, then move again three times from the back tothe front during a third movement phase, etc.

Thus, the cleaning robot autonomously makes various movements on thebottom of the pool, without any user action. During a movement phase,the cleaning robot may get stuck against a vertical side of the pool andremain stuck for many seconds whilst waiting for a movement phase thatwill command the cleaning robot to move away from said vertical side.

Many systems have been proposed to detect when the cleaning robot getsstuck against a vertical side. For example, a cleaning robot maycomprise a mechanical contactor adapted to come into contact with thevertical wall. When the mechanical contactor is activated, it orders amodification of the movement phase. Such a mechanical contactor presentsthe disadvantage of exercising a mechanical force against the verticalside of the pool which is usually covered with a coating known to a manof the art under the English term “liner”. The repetitive pressing ofthe liner contactor may damage said coating and thus affect itslifespan. What is more, the mechanical contactor must remain watertight,which increases the complexity and the cost of such a detection system.

We know of a pool-cleaning robot from the prior art, in patentapplication U.S. Pat. No. 6,758,226, that aims to eliminate thisdisadvantage, which comprises a detection system that comprises an idlerwheel adapted to be in contact with the base of the pool during themovement of the cleaning robot, a transmitter adapted to issue a beam oflight and a receiver adapted to receive said beam of light. The axialrunout of the detection wheel has an orifice drilled in it through whichthe beam of light may circulate when said orifice is aligned with thetransmitter and the receiver. Thus, the receiver intermittently receivesthe beam of light during the rotation of the detection wheel and maydeduce that the detection wheel is moving. In contrast, when thereceiver does not detect any variation in light, it may deduce that thecleaning robot is stuck.

Such a detection system has many disadvantages. First of all this has avery significant size owing to the presence of an idler wheel dedicatedto detection and the transmitter and the receiver which must be placedeither side of the idler wheel. Owing to its size, it is hard tointegrate the detection system into the cleaning robot which alreadycomprises a motorised transport system and a detritus suction system. Inpractise, the idler wheel must be placed in the centre of the robot toensure that it does not impede the movement of the cleaning robot via a“crutch effect”. What is more, the idler wheel must be pushed up againstthe floor using an elastic spring, which also penalises its size.Finally, the cost of such a detection system is very high.

Incidentally, we also know of an infrared detection system whichcomprises a front infrared transmitter/receiver and a rear infraredtransmitter/receiver in order to detect the vertical sides of the poolduring the movement, forwards or backwards, of the cleaning robot. Sucha detection system is complex to implement given that the presence ofalgae on the vertical sides of the pool disrupts detection. It istherefore necessary to envisage high power infraredtransmitters/receivers, which are costly. For this reason, such adetection system is only mounted on large cleaning robots, used forpublic swimming pools, in particular.

The invention therefore aims to propose a cleaning robot that comprisesa cost-effective detection system that is small in size.

SUMMARY

To this end, the invention concerns a pool-cleaning robot comprising atransport system that comprises at least one idler wheel transporttrain, a detritus suction system and a immobilisation detection systemfor said cleaning robot, the detection system comprising at least onetransmitter-receiver for a beam of light along an emission axis and atleast one target that is part of said transport wheel train and alignedwith said emission axis, adapted to reflect said beam of light in orderto detect the rotation of said transport wheel train.

By transport wheel train, we mean an integral rotating assemblycomprising at least two wheels connected by at least one axle.

Thus, the transport wheel train advantageously participates in themovement of the cleaning robot. The detection system according to theinvention does not require an additional wheel dedicated to detection tobe added, as in the prior art, which limits the complexity, the size andthe cost of such a cleaning robot. What is more, a transmitter-receiveralso improves the size and reduces the constraints associated with watertightness in comparison with an assembly comprising a transmitter and areceiver. Also, since the detection is carried out over a shortdistance, a low power, low-cost transmitter-receiver may be used.

The transport system may be a hydraulic propulsion system, in which caseall the transport wheel trains are idle mounted. Alternatively, thetransport system may be motorised and comprise a motorised transportwheel train and an idler wheel train.

The detection system preferably comprises a watertight housing in whichthe transmitter-receiver is mounted. Said watertight housing preferablycomprises a transparent side to allow light beams to travel along saidemission axis. The transmitter-receiver may therefore be practicallymounted inside the watertight housing by turning its emission axistowards the transparent side. The housing may then be mounted inside thecleaning robot as a standalone module. Such a detection system has a lowmanufacturing cost and is simple to integrate into a cleaning robotwithout affecting its size.

Again, the housing is preferably entirely transparent. This avoids theneed to envisage a dedicated transparent side, which is costly andcomplex to assemble whilst maintaining water tightness.

The transmitter-receiver is preferably an infrared transmitter-receiverin order to limit its electrical consumption and cost, with the infraredtransmitter-receiver preferably having a wavelength of between 800 nmand 1100 nm and this preferably being 940 nm.

The detection system is, preferably, connected to a power supply unitthat has been adapted to be connected to an electrical cable. Thedetection system and the transport system are preferably connected tothe same power supply unit.

The target preferably comprises an alternating pattern of reflectiveareas and non-reflective areas. Thus, the transmitter-receiverintermittently receives a beam of reflected light during rotation of thetransport wheel train. Such a target is advantageous since it may bepractically mounted to any part of the transport wheel train (wheel,axle, fin, etc.).

The transport wheel train preferably comprising at least two wheelslinked by an axle, said target is fixed to said axle. Attaching thetarget to the axle rather than to the wheels provides the benefit ofreducing the target size since the axle is smaller in diameter than thewheel. What is more, attaching it to the axle provides the benefit ofproviding more mounting space, the mounting space near a wheel beinglimited.

The target is, preferably, ring-shaped and attached to the edge of alongitudinal portion of the axle. The target is, preferably, positionednear to the centre of the axle, with it then being possible to reservethe lateral space of the cleaning robot for the transport system(wheels, side discharge orifices, etc.).

The cleaning robot, preferably, comprising a front wheel and rear wheeltrain, with each wheel train comprising an axle, said detection systemis attached near to the rear axle so that it remains close to thetransport system, facilitating their power supply and the sending of thecommand from the detection system to the transport system.

The emission axis, preferably, extends orthogonally to the axis ofrotation of the wheel, preferably vertically, so as to not limit thespace for the detritus suction system. What is more, such a layoutallows the length of the cleaning robot to be limited.

The cleaning robot, preferably, comprises a single transmitter-receiverand a single target in order to limit its size and its complexity.

According to another embodiment, the target is attached to one of theidler wheels of the transport train. The emission axis, preferably,extends parallel to the axis of rotation of said wheel.

Said target is, preferably, attached by gluing. This advantageouslyallows a detection system to be practically adapted to a classiccleaning robot.

The transport system, preferably, also comprises a motorised transportwheel train. Thus the cleaning robot may move around independently.According to another aspect, the transport system has hydraulicpropulsion and only comprises idler wheel transport trains.

The invention also concerns an immobilisation detection method for apool-cleaning robot such as that presented above, with the cleaningrobot moving according to a movement phase, with the method comprisingthe following:

-   -   a step in which said transmitter-receiver emits a beam of light        along the emission axis towards said target,    -   an intermittent reception step in which said        transmitter-receiver receives a beam of light reflected by said        target, and    -   a step in which the movement phase for said cleaning robot is        modified when said transmitter-receiver does not receive any        beam of light for a set length of time or when it receives a        beam of light for a set length of time.

Thus, immobilisation is detected when the beam of reflected light is nolonger received intermittently. Such a method advantageously allows thecleaning of a pool to be sped up by modifying the movement of thecleaning robot when it is prevented from moving.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention shall be better understood on reading the descriptionbelow, given for example only, and which refers to the attacheddrawings, in which:

FIG. 1 is a schematic representation in perspective of a cleaning robotaccording to an embodiment of the invention;

FIG. 2 is a side view of the robot from FIG. 1;

FIG. 3 is a rear view of the robot from FIG. 1, without its main body;

FIG. 4 is a close-up of the robot from FIG. 3 for which a cross-sectionof the detection system is shown;

FIG. 5 is a close-up of the detection system from FIG. 4;

FIGS. 6 and 7 are schematic representations of the detection system whena beam of light is or is not reflected; and

FIG. 8 is the representation of a detection signal when the cleaningrobot is immobilised.

It should be noted that the figures show the invention in detail forimplementation of the invention, said figures may, of course, be used tobetter define the invention, where applicable.

DETAILED DESCRIPTION

A pool-cleaning robot 1 as per an embodiment of the invention ispresented in FIGS. 1 to 3.

The cleaning robot 1 comprises a main body 10 which extendslongitudinally along an axis X oriented from the back to the front. Asshown in FIG. 3, the cleaning robot 1 comprises a front wheel train 11and a rear wheel train 12. Each train 11, 12 comprises an axle 110, 120,each of which has transport wheels 2 at its extremities. The wheels 2are adapted to come into contact with the bottom of a pool and hold themain body 10 of the cleaning robot 1 at a set distance from said poolbottom. A cleaning robot 1, comprising two wheel trains 11, 12 ispresented but it is obvious that it could have a different number ofthem. Likewise, it is obvious that the invention applies to a cleaningrobot 1 comprising a different number of wheels 2, e.g. three.

With reference to FIG. 1, the cleaning robot 1 comprises a handle 3 onthe front to allow a user to lift the cleaning robot into a verticalposition.

With reference to FIG. 3, the cleaning robot 1 comprises a detritussuction system 5 in the form of a pump which is housed in main body 10.The detritus suction system 5 comprises a suction aperture verticallyoriented downwards and a discharge aperture. The detritus suction system5 also comprises a housing for collecting detritus which is positionednear the suction aperture to store the detritus collected.

The detritus suction system 5 is, preferably, connected to a powersupply unit that has been adapted to be connected to an electricalcable.

In this example, with reference to FIG. 1, the cleaning robot 1comprises a transport system with hydraulic propulsion 4 which comprisesa plurality of water outlets, in particular, a front outlet 42 a, acentral rear outlet 42 b and two side outlets 42 c. Such a transportsystem 4 is known to a man of the art, and from patent application FR1254892, in particular. The transport wheel trains 11, 12 are idlermounted, i.e. they do not have any mechanical drive. The wheels 2 thusessentially allow the cleaning robot 1 to be guided.

In this example, the transport system 4 comprises a mobile unit (notshown) which is mounted between the discharge aperture for the detritussuction system 5 and the water outlets 42 a-c to orient the flow ofwater towards a predetermined water outlet 42 a-c. It is obvious thatthe transport system 4 may comprise a different number of outlets. It isalso obvious that the positioning of said outlets may be different.

The transport system 4 also comprises a management module (not shown)which defines the movement phases of the cleaning robot 1 and, to thisend, controls the orientation of the mobile unit. The management modulepreferably comprises a circuit that has a microprocessor, and a memorywhich stores the sequence of the transport phases, in particular, theduration and the type of transport during a movement phase (movementfrom front to back, movement to the side, etc.).

According to the invention, with reference to FIG. 5, the detectionsystem 6 comprises a transmitter-receiver 7, adapted to emit and receivea beam of light L along an emission axis, and a target 8 that isintegral with transport wheel train 12 and aligned with said emissionaxis, adapted to reflect said beam of light L so that the rotation ofsaid transport wheel train 12 can be detected. Thus, the detectionsystem 6 allows the rotation of the wheels to be monitored in apractical manner, whilst keeping the size down, as shall be presentedbelow.

The detection system 6 is connected to the management module of thetransport system 4 in order to allow the movement phase defined by themanagement module to be modified in the event that movement preventionhas been detected. As presented below, in the event that movement isprevented, the detection system 6 commands the transport system 4 tomove in the opposite direction in order to release the cleaning robot 1.

In this example, with reference to FIGS. 4 and 5, thetransmitter-receiver 7 comprises a watertight housing 70, preferablycylindrical in form, which houses a circuit board 71 on which anelectronic component 72, adapted to emit and receive a beam of light Lalong an emission axis is mounted. The electronic component 72 ispreferably a SMC component (Surface-Mounted Component).

The electronic component 72 is, preferably, configured to issue a beamof light L, infrared in particular, over a short distance in order tohave a limited cost. The electronic component 72 is preferablyconfigured to emit an infrared beam with a wavelength of between 800 nmand 1100 nm and this, in particular, being 940 nm. For example, anelectronic component, known under the commercial name AGILENT HSDL 9100,may be sufficient.

With reference to FIGS. 6 and 7, the watertight housing 70 comprises atransparent side 73 in order to allow the beam of light L to enter saidhousing 60 along said emission axis. The transparent side 73 extendsrelative to the target 8. In this example, the watertight housing 70 isentirely transparent.

The transmitter-receiver 7 is preferably connected to an electricitysupply unit, the same as that for the detritus removal system 5 and thatfor the transport system 4 in particular.

With reference to FIG. 3, the transmitter-receiver 7 is fixed to themain body 10 of the cleaning robot 1 and positioned near the rear axle120 of the cleaning robot 1. Positioning to the rear is advantageousgiven that the front space is occupied by the detritus suction system 5and by the handle 3.

As illustrated in FIG. 5, the transmitter-receiver 7 is positioned overthe rear axle 120 so as to limit the length and provide as much space aspossible for the detritus suction system 5 and the transport system 4.

The transmitter-receiver 7 advantageously presents itself in the form ofa small standalone module which may be easily dismantled and replaced.What is more, its water tightness is simple to ensure, since there areno moving parts. The cleaning robot 1 preferably comprises only onetransmitter-receiver 7 in order to reduce the cost of the cleaning robot1.

Target 8

With reference to FIG. 5, a target 8 fixed to the rear axle 120 isrepresented in order to allow the indirect detection of the rotation ofthe transport wheel train 12 by monitoring the rear axle 120. Suchindirect monitoring is especially advantageous as regards to size andcomplexity since it allows the general structure of the cleaning robot 1to be left untouched, keeping two parallel axles 110, 120 of simpledesign. To this end, the emission axis of the beam of light L extendsorthogonally to the axis of rotation of the wheel 2.

Detection of immobilisation of the wheels 2 of the rear axle 120 hasbeen presented, but it is obvious that the invention also applies to theimmobilisation detection of the wheels 2 of the front axle 110.Likewise, the invention also concerns detection of a target 8, directlyattached to a transport wheel 2. To this end, the emission axis of thebeam of light L extends parallel to the axis of rotation of the wheel 2.

The distance between the transmitter-receiver 7 and the target 8 ispreferably between 3 and 100 mm, preferably between 3 and 10 mm. Thus, alow-power and low-cost transmitter-receiver 7 is sufficient.

In this example, as shown in FIGS. 5 to 7, the target 8 is ring-shapedand extends around a longitudinal portion of the rear axle 120 of therear transport wheel train 12. The target 8 comprises an alternatingpattern of reflective areas 81 and non-reflective areas 82. In thisexample, the reflective areas 81 are created using a reflective metalcoating whereas the non-reflective areas 82 are created using a blackmat coating. Alternatively, the target 8 may comprise a plurality offins or pales, some of which are reflective and others of which are notreflective.

The reflective areas 81 and the non-reflective areas 82 are preferablyof the same dimensions so that the transmitter-receiver 7 measures aregular signal when the cleaning robot 1 moves at constant speed.

An example of embodiment of the invention shall now be presented withreference to FIGS. 6 to 8.

The cleaning robot 1 is on the bottom of the pool and connected to apower supply cable (not shown) in order to allow, on the one hand,suction of detritus and, on the other hand, a transport of cleaningrobot 1 based on the movement phases recorded in the management moduleof the transport system 4.

If there are no obstacles, the cleaning robot 1 moves at a substantiallyconstant speed, the idler wheel transport trains 11, 12 then rotatealong with their axles 110, 120 and the transport wheels 2. Withreference to FIG. 2, the cleaning robot 1 moves over the horizontal sideof the pool SH.

The target 8 thus rotates with the rear axle 120 and reflects the beamof light L emitted by the electronic component 72 of thetransmitter-receiver 7 when a reflective area 81 is aligned with theemission axis (FIG. 6). The reflected beam of light L is received by theelectronic component 72 of the transmitter-receiver 7 which generates ahigh T₈₁ signal (FIG. 8).

In contrast, when a non-reflective area 82 is aligned with the emissionaxis (FIG. 7), the electronic component 72 of the transmitter-receiver 7does not receive any beam of light L and generates a low T₈₂ signal(FIG. 8).

In other words, when the cleaning robot 1 is moving, the signalgenerated is substantially regular. When the cleaning robot 1 is stuck,e.g. when the cleaning robot 1 is butting up against a vertical sideS_(V), for example, a reflective area 81 or a non-reflective area 82 isaligned with the emission axis for a long period of time, thusgenerating a high T₈₁ or low T₈₂ value for a long period of time.According to the invention, we define a timeout T_(S) after which thetransmitter-receiver 7 issues a movement phase change instruction INS tothe management module of the transport system 4. The timeout T_(S) ispreferably between 2 s and 10 s, preferably 5 s, in order to rapidlycommand a change in movement of the cleaning robot 1 on detection of anobstacle.

In this example, with reference to FIG. 8, since the non-reflective area82 is aligned with the emission axis for a duration greater than saidtimeout T_(S), the transmitter-receiver 7 sends a movement phase changeinstruction INS to the management module of the transport system 4 sothat the cleaning robot 1 moves away from the vertical side S_(V) thatthe cleaning robot 1 was butting up against. In this example, thedetection system 6 commands movement in the opposite direction in caseof immobilisation.

Thanks to the invention, the cleaning robot 1 may practically detect anyobstacle during cleaning (side, branch, etc.) in order to modify itsmovement and thus clean the pool. What is more, the detection system 6may advantageously measure and monitor the speed of movement of thecleaning robot 1.

The invention has been presented for the cleaning robot 1 comprising atransport system with hydraulic propulsion but it also applies to amotorised transport system comprising at least one motorised transportwheel train in addition to the idler transport wheel trains.

1. Pool-cleaning robot comprising a transport system comprising at leastone idler transport wheel train, a detritus suction system and animmobilisation detection system of said cleaning robot, the detectionsystem comprising: at least one transmitter-receiver for a beam of lightalong an emission axis and at least one target, integral with thetransport wheel train and aligned with said emission axis, adapted toreflect said beam of light in order for the rotation of said transportwheel train to be detected.
 2. Cleaning robot according to claim 1, inwhich the detection system comprises a watertight housing in whichtransmitter-receiver is mounted, said watertight housing comprising atransparent side to allow the circulation of beams of light according tosaid emission axis.
 3. Cleaning robot according to claim 1, in which thetransmitter-receiver is an infrared transmitter-receiver.
 4. Cleaningrobot according to claim 1, in which the target comprises an alternatingpattern of reflective areas and non-reflective areas.
 5. Cleaning robotaccording to claim 1, in which, the transport wheel train comprising atleast two wheels connected by an axle, said target is attached to saidaxle.
 6. Cleaning robot according to claim 5, in which thetransmitter-receiver is positioned over said axle.
 7. Cleaning robot,according to claim 1, in which said target is attached by gluing. 8.Cleaning robot according to claim 1, in which the transport systemfurther comprises a motorised transport wheel train.
 9. Cleaning robotaccording to claim 1, in which the transport system comprises severalidler wheel transport trains.
 10. Immobilisation detection method for apool-cleaning robot according to claim 1, the cleaning robot moving inaccordance with a movement phase, the method comprising: a step in whichsaid transmitter-receiver emits a beam of light along the emission axistowards said target, an intermittent reception step in which saidtransmitter-receiver receives a beam of light reflected by said target,a step in which the movement phase for said cleaning robot is modifiedwhen said transmitter-receiver does not receive any beam of light for aset length of time or it receives a beam of light for a set length oftime.